AirHint found the following cheapest return flights from Boston (BOS) to Sao Paulo (GRU) in September 2025 (see full year).

Return flights

13 Sep - 19 Sep	Avianca
22 Sep - 25 Sep	Copa
16 Sep - 30 Sep	Copa
09 Sep - 16 Sep	Copa
08 Sep - 15 Sep	Avianca
02 Sep - 24 Oct	GOL Linhas Aéreas
21 Sep - 24 Sep	Copa
04 Sep - 03 Oct	Copa
04 Sep - 13 Sep	Copa
17 Sep - 27 Sep	Copa
18 Sep - 28 Sep	Copa
02 Sep - 15 Sep	Copa
15 Sep - 01 Oct	Delta	direct
04 Sep - 03 Oct	Delta	direct

Also check the deals for one-way flights from Boston to Sao Paulo in September.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Boston to Sao Paulo in September from 421€

Return flights